The importance of gaps and dwarf trees in the regeneration of Swedish spruce forests: the origin and content of Sernander's (1936) gap dynamics theory

This article is a review of a classic paper (1936) by the late Professor Rutger Sernander. This work by Sernander includes the very first formulations of a general theory about forest dynamics driven by storm fellings in fire refugia. Sernander discussed forest dynamics on three different scales: at the landscape, stand and individual tree scale. This article discusses all the important variables and the different stages in forest dynamics brought up by Sernander, such as different susceptibility to storm damage of stands growing on different soil types, the importance of different wind directions and speed, and differences between tree species with regard to susceptibility to wind. It also discusses differences in gap sizes and forms, decomposition degrees of fallen trees, different regeneration modes in connection with gap creation, the effects of wind disturbance on the field-layer vegetation and other stand characteristics, as observed by Sernander.